Private Thomas Lawless of Calgary was laid to rest in La Chaudière Military Cemetery in Vimy, France, on March 15—94 years after he gave his life in service of his country.

It was also more than seven years after his remains had been recovered, along with those of a comrade, by workers excavating for a gas pipeline in nearby Avion in 2003.

On July 8-9, 1917, Lawless and his comrade Pte. Herbert Peterson of Berry Creek, Alta., both of the 49th Battalion, Canadian Infantry, were part of a force of more than 200 that surged forward through the midnight rain and haze under cover of a rolling barrage and machine-gun fire in a raid on German trenches. The raiders were successful, bombing dugouts, capturing or destroying machine-guns, taking 136 prisoners and leaving behind an estimated 700 German casualties. The Germans later abandoned these trenches.

But 38 of the raiders were also killed, some by covering artillery bursts that fell short of the target into the advancing ranks, others by German defensive fire. “There is an eyewitness account of Lawless being killed by a blast,” says Laurel Clegg, casualty identification co-ordinator with the Department of National Defence’s Directorate of History and Heritage in Ottawa. Lawless was among 16 dead not recovered at the time.

More than 66,000 Canadians were killed in the First World War, about 19,500 of whom have no known grave and whose names are immortalized on the Vimy Memorial in France and on the Menin Gate in Belgium, among others. Many lie in graves in France and Belgium with headstones marked Known Unto God.

Farmers and construction workers still unearth the remains of those killed nearly a century ago. It is the job of Clegg and her colleagues to put names to the bones and artifacts, aided by historical record, forensic skills and the tools of modern technology, such as DNA matching and use of isotopes.

DNA matching with living descendants was the clincher in identifying Peterson, whose remains were found at the same time (Finding Names For Long-Lost Canadian Soldiers,  January/ February, 2009). He was buried in La Chaudière Cemetery in 2007. But the DNA samples from the second set of remains were too deteriorated.

So it was decided to start over. Enter University of Western Ontario anthropology professors Andrew Nelson and Christine White and earth science professor Fred Longstaffe in London, Ont. Nelson examined the bones, giving a new estimate of height, weight and age from the remains. Some of the remaining 15 unidentified soldiers from that night were eliminated because they were too old, too young, too tall or too short. Five candidates remained.

Nelson and Steve Kruithof of the National Research Council of Canada created a computer model of the skull, then made a 3-D print which was used by Newfoundland forensic artist Christian Corbet to create a reconstruction.

That information and new DNA samples from living descendants whittled the number of candidates down to two. “Then we were stuck again,” said Clegg. Then she attended a conference where she heard about forensic use of stable oxygen isotopes.

The composition of oxygen in drinking water varies around the world according to latitude, altitude, elevation and wind patterns, and leaves a signature in the oxygen isotopes incorporated into teeth. It’s possible to tell where in the world a person was born and grew up based on differences in these isotopic signatures. Although the two remaining candidates had both lived in Alberta before going to France, they had been born and raised in different locations. Clegg asked Janet Roy, the genealogy co-ordinator in Thunder Bay, Ont., who found descendants for DNA testing, “for a year-by-year record of where each of these guys lived.” One came from Cape Breton, the other from Ireland.

The isotopes from the teeth in the remains were compared to data recorded by the International Atomic Energy Agency, which tracks oxygen isotope composition around the world. Longstaffe matched the isotopic signature in the teeth to that of Ireland. Thomas Lawless had finally been identified.

He was finally laid to rest after a military funeral attended by relatives from Ireland, alongside his comrade Herbert Peterson in a graveyard in foreign fields, far from Alberta where they had enlisted to fight for their country. They are buried about two kilometres from where their remains were found, near 14 other members of the 49th Battalion killed in the same raid.

Meanwhile, the grim harvest continues from battlefields in Europe and other places around the world where Canadians have fought and died. Canada has about 30,000 soldiers from various conflicts with no known grave, and at any one time the department has between 50 and 60 sets of unidentified remains. Clegg and her colleagues work doggedly on.